The present invention relates to a cooling system for a three-dimensional IC package and, more particularly, to a cooling system for a package having a plurality of laminated substrates mounting ICs thereon.
Recently, the degree of integration of semiconductor devices has improved, the sizes of printed circuit boards or ceramic substrates have increased, and the number of mounted devices per substrate has increased. As a result, the packing density of ICs has significantly improved. As the total amount of heat generated in ICs is increased, a demand has arisen for a cooling technique having high performance and good efficiency. In particular, large apparatuses have adapted a conductive cooling system in which a heat radiating surface of an IC is thermally connected to a member called a cold plate having a cooling fluid path therein.
A typical example of the conductive cooling system according to a conventional technique is disclosed in U.S. Pat. No. 4,245,273. In this conventional technique, a cap structure is mounted on a substrate on which a plurality of ICs are mounted. This cap has a plurality of conductive pistons biased downwardly into contact with the IC devices by springs, respectively. On the top surface of this cap, a cooling jacket in which a suitable cooling fluid can be circulated is mounted.
Recently, in order to increase the packing density of ICs, a three-dimensional IC package in which a plurality of substrates each mounting ICs thereon are laminated with a small interval therebetween has been adopted. In such a three-dimensional IC package, since the requirement for the interval between the substrates is strict, it is difficult to adopt the cap structure according to the above conventional technique. In addition, maintainability is degraded as the size of the substrate is increased, resulting in high cost.